Hydraulic actuated pump system

ABSTRACT

The invention is directed to a hydraulic actuated pump system which lifts production fluids and re-circulating hydraulic fluid from a petroleum well. Additives may be added to the hydraulic fluid to apply direct chemical treatment to the production formation. A sonic stimulator may be included to stimulate and produce the same liquids from the horizontal section of the well.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 13/287,265 filed on Nov. 2, 2011, which is a divisionalapplication of U.S. patent application Ser. No. 12/246,255 filed on Oct.6, 2008, now U.S. Pat. No. 8,069,914 issued on Jun. 12, 2011, whichapplication claimed the priority of U.S. Provisional Patent Application60/978,007 filed Oct. 5, 2007, entitled “Hydraulic Actuated Pump System,the entire contents of which are incorporated by reference.

FIELD OF THE INVENTION

The present invention relates to a hydraulic actuated pump system andsonic stimulation tools for downhole applications.

BACKGROUND OF THE INVENTION

Within a petroleum producing well, the production string forms theprimary conduit through which production fluids (liquids, gases, or anyfluid produced from a wellbore) are produced to the surface. Theproduction string is typically assembled with production tubing andcompletion components in a configuration that suits the wellboreconditions and the production method. Oil wells typically vary from afew hundred to several thousand feet in depth, and there is ofteninsufficient formation pressure to cause the flow of production fluidsthrough the production string to the surface.

Several prior art systems involving different pumping and extractiondevices have been developed for the surface transfer of productionfluids from a well. Downhole hydraulic pumps installed deep within thewell are commonly used. A surface hydraulic pump pressurizes power oilwhich drives the downhole pump. When a single production string is used,the power oil is pumped down the tubing and a mixture of the formationcrude oil and power oil are produced through the casing-tubing annulus.If two production strings are used, the power oil is pumped through oneof the pipes, and the mixture of formation crude oil and power oil areproduced in the other, parallel pipe.

Prior art artificial lift systems include for example, the progressivecavity pump and plunger lift, both of which are installed on jointed orcontinuous rods; electric submersible pumps; gear pumps installable ontubing and powered by downhole electric or hydraulic motors; and theventuri lift which is run on coiled tubing but is not a total productionsystem. However, such systems tend to be complex and/or of substantialsize and weight, requiring significant structural support elements atthe wellhead which increase the expense of the overall system.

SUMMARY OF THE INVENTION

The present invention is directed to a hydraulic actuated pump system.In one aspect of the invention, the invention comprises a pump systemfor lifting production fluids to the surface or circulating servicefluids in a wellbore, comprising:

-   -   (a) a cylindrical outer tubular member and an cylindrical inner        tubular member in a concentric orientation therewith, defining        an annular bore therebetween;    -   (b) a production packer sealing the annular bore in a downhole        location proximate a production zone;    -   (c) means for pumping hydraulic fluid from the surface into the        annular bore;    -   (d) wherein the inner tubular member defines an inner bore        extending therethrough to allow upward passage of a mixture of        hydraulic fluid and production fluids from the wellbore, wherein        the inner bore is open to the production zone;    -   (e) a plurality of jet members spaced intermittently along the        wellbore, wherein each jet member defines at least one jet        nozzle providing fluid communication from the annular bore to        the inner bore;    -   (f) wherein the at least one jet nozzle is adapted and oriented        to provide a high velocity hydraulic fluid stream into the inner        bore thereby providing a lift force to fluid in the inner bore.

In one embodiment, the jet members comprise a plurality of nozzleshaving diameters sized to project fluid streams. In one embodiment, thedownhole assembly may include one or more of a production packer, areciprocating bit, a sonic stimulator, a sonic stimulator with areciprocating bit, a drill motor with a drill bit, or a drill motor witha casing reaming assembly. In one embodiment, the downhole assemblycomprises a production packer having threaded hold-down slips, threadedset-down slips, and packer elements positioned between the hold-downslips and set-down slips to seal against an inner wall of the productioncasing.

In one embodiment, the downhole assembly comprises a sonic stimulatorfor emitting pressure waves into the formation production zone. In oneembodiment, the sonic stimulator comprises an elongate body defining abore extending therethrough, a plurality of tubular jet members, and ahydraulic coupling which generates pulsed pressure waves. In oneembodiment, at least one of the jet members includes a nozzle.

In one embodiment, the sonic stimulator comprises an elongate bodydefining a bore extending therethrough to house a valve retainer, avalve, a plurality of jet members, a resonance assembly, a rod retainer,a piston assembly moveable between a first position and a secondposition, and biasing means for biasing the piston towards the firstposition. In one embodiment, the jet members comprise one or morenozzles. In one embodiment, the jet members are rotatable. In oneembodiment, the biasing means comprises a coil spring.

In one embodiment, the hydraulic fluid comprises water, produced water,water-based fluids, water-oil emulsions, inorganic salt solutions,biodegradable plant-based hydraulic fluids, or synthetic or naturallyoccurring organic materials. In one embodiment, the hydraulic fluid issupplemented with one or more additives selected from oils, butanol,esters, silicones, alkylated aromatic hydrocarbons, polyalphaolefins, orcorrosion inhibitors. In one embodiment, the one or more additivescomprise a brine-based, heavy oil chemistry for creating a lightoil-in-water emulsion within the production fluids. In one embodiment,the supplemented hydraulic fluid is sonified. In one embodiment, thehydraulic fluid or the supplemented hydraulic fluid is heated to atemperature ranging from about 30° to about 101° C.

In another aspect, the invention may comprise a sonic stimulator fordownhole use in a petroleum well, comprising:

-   -   (a) an inlet for receiving a hydraulic fluid under pressure;    -   (b) a wave generator for generating an acoustic wave as the        hydraulic fluid passes through the wave generator; and    -   (c) a jet member for exhausting the hydraulic fluid from the        sonic stimulator.

In another aspect, the invention may comprise a method of enhanced oilrecovery from a formation, comprising the steps of:

-   -   (a) installing a sonic stimulator into a wellbore;    -   (b) activating the sonic stimulator with a hydraulic power fluid        to produce acoustic waves and inject the hydraulic power fluid        into the formation;    -   (c) using the hydraulic power fluid to sweep heavy oil towards a        production well.        The hydraulic power fluid may comprise one or more additives to        assist in mobilization or emulsification of the heavy oil. The        addition of the additives may be tapered so as to place the        additives in specific portions of the wellbore. The additives        may comprise an alkaline component and a surfactant component.

In one embodiment, the wellbore is a production well, and comprises avertical portion, and a horizontal portion, and the additives are addedso as to place the additives in a toe portion of the horizontal portion.Alternatively, the wellbore may comprise an injection well, and isproximate one or more production wells.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described by way of an exemplary embodimentwith reference to the accompanying simplified, diagrammatic,not-to-scale drawings.

FIG. 1 is a schematic cross-sectional view of a pump system of oneembodiment of the present invention.

FIG. 1 a is a diagrammatic representation of a tubular jet member of apump system of FIG. 1.

FIG. 2 is a diagrammatic representation of a pump system of oneembodiment of the present invention.

FIG. 3 is a diagrammatic representation of a pump system of FIG. 2 inconnection with surface components.

FIG. 4 is a diagrammatic representation of a pump system of oneembodiment of the present invention, including a sonic stimulator.

FIG. 5 is a diagrammatic representation of a pump system of FIG. 4 inconnection with surface components.

FIG. 6 is a diagrammatic representation of a sonic stimulator of oneembodiment of the present invention.

FIG. 7 is a diagrammatic representation of a sonic stimulator of FIG. 6,showing the pathway of hydraulic fluid.

FIG. 8 is a diagrammatic representation of an exploded view of ahydraulic drive of the sonic stimulator of FIG. 6.

FIG. 9 is a diagrammatic representation of a sonic stimulator of oneembodiment of the present invention.

FIG. 10 is a diagrammatic representation of a hydraulic drive unit ofthe sonic stimulator of FIG. 9.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides for a hydraulic actuated pump system.When describing the present invention, all terms not defined herein havetheir common art-recognized meanings. To the extent that the followingdescription is of a specific embodiment or a particular use of theinvention, it is intended to be illustrative only, and not limiting ofthe claimed invention. The following description is intended to coverall alternatives, modifications and equivalents that are included in thespirit and scope of the invention, as defined in the appended claims.

“Horizontal” means a plane that is substantially parallel to the planeof the horizon. “Vertical” means a plane that is perpendicular to thehorizontal plane. One skilled in the art will recognize that wellboresmay not be strictly vertical or horizontal, and may be slanted or curvedin various configurations.

The hydraulic actuated pump system (1) lifts production fluids andre-circulating hydraulic fluid from the wellbore. The hydraulic fluid ispressurized to drive the system. Additives may be added to the hydraulicfluid to apply direct chemical treatment to the production formation. Asonic stimulator may be included in conjunction with the pump system tostimulate and produce the same liquids from the well.

In one embodiment, the system may be applied to a well having asubstantially vertical portion, and a substantially horizontal portion.Horizontal directional drilling to create such a wellbore is well knownin the art.

The pump system (1) is shown schematically in FIG. 1 in a vertical welland comprises an outer tubular member (10), an inner tubular member(12), a plurality of jet members (14), a plurality of crossover members(16), and a downhole assembly (18). The well is cased with conventionalwell casing (20). As the annulus (36) between the pump system (1) andthe production casing (20) is not necessarily used to transport fluidswithin the well, the pump system may be sized to fit within the casingto a close tolerance.

The outer tubular member (10) is generally cylindrical and houses theinner tubular member (12) in a concentric orientation therewith, formingan annular bore (22) to allow passage of hydraulic fluid (indicated byarrow “a”) through an inlet (24) from the surface. As used herein and inthe claims, the term “concentric” refers to components sharing a commoncenter and thus a uniform annular dimension. However, two tubularmembers where one has a smaller diameter and is placed within the othermay be considered concentric, even if they do not share the exactgeometric centre, and even if they are not circular in cross-section.

The inner tubular member (12) is preferably generally cylindrical anddefines an inner bore (26) which is open to the production zone of theformation. In one embodiment, the outer and inner tubular members (10,12) are concentric coil or jointed tubular members. A coiled tubularmember comprises a continuous length of tubing, while a jointed tubularmember comprises lengths of tubing joined together by suitableattachment means. Both coiled and jointed tubing are well known in theart and further description is not needed.

A production packer (18) is provided as part of the downhole assembly toisolate the annular space between the inner and outer tubular membersfrom the inner bore (26) of the inner tubular members.

A plurality of jet members (14) are provided along the length of theinner tubular members (12), spaced intermittently along the length ofthe wellbore. In one embodiment, the jet members (14) form part of theinner tubular string, and comprise at least one nozzle (30) havingdiameters sized to project streams of pressurized fluid (FIG. 1 a). In apreferred embodiment, a plurality of nozzles are arrayedcircumferentially about the diameter of the jet member (14) and areaimed upwards. In one embodiment, the nozzles (30) are convergent,narrowing from a wide diameter to a smaller diameter to accelerate fluidflow. In operation, power fluid is pumped into the annular space at highpressure. Because the annular space is closed by the production packer,the power fluid flows through the jet member nozzles (30) upwards intothe inner bore. The jet members (14) create a high velocity flow upwardsinto the inner bore, creating a venturi effect and sucking productionfluid upwards in the inner bore.

The jet members (14) may be centralized within the annulus by portionsin contact with the outer tubular members, as shown schematically inFIG. 1. In this case, sufficient openings in the annular bore to allowpower fluid to reach lower jet members must of course be provided.Alternatively, the jet members may form part of inner tubular string,and not contact the outer tubular members, as shown in FIG. 2.

Crossover members (16) are included to connect components with differentthread types or sizes. In one embodiment, a crossover member (16 a) issized to connect and cap the outer and inner tubular members (10, 12) atthe surface, and defines an aperture (34) through which the outlet means(28) extends to the surface. In one embodiment, a crossover member (16b) connects the outer and inner tubular members (10, 12) with thedownhole assembly (18).

The downhole assembly may comprise one or more of a variety ofcomponents including, for example, a production packer (18), areciprocating bit, a sonic stimulator, a sonic stimulator with areciprocating bit, a drill motor with a drill bit, a drill motor with acasing reaming assembly, or other suitable components known to thoseskilled in the art. In one embodiment, the downhole assembly comprises aproduction packer (18) for anchoring the tubular members (10, 12) andisolating the annulus (36) from the production formation. The productionpacker (18) may comprise threaded hold-down slips (18 a), threadedset-down slips (18 b), and packer elements (18 c) (for example, rubberO-rings) positioned between the hold-down slips (18 a) and set-downslips (18 b) to seal against the inner wall of the production casing(20) to isolate the well's annulus (36) from the production formation.Tail pipe or lower completion elements (18 d) are mounted below theset-down slips (18 b).

In one embodiment shown in FIG. 2, the casing (20) has a plurality ofperforations (38) at its end (40) to enable fluid communication with theformation production zone, namely the target reservoir rock containingproduction fluids including, for example, water, oil, condensates, ornatural gas. FIG. 3 shows this embodiment of the invention in connectionwith surface components.

In operation, hydraulic power fluid (as indicated by arrows “a”) isplaced into a recirculation tank (42) at the surface. The operation of arecirculation tank (42) is commonly known to those skilled in the artand will not be discussed in detail. Briefly, the recirculation tank(42) for preparing power fluid is generally configured with a tank, apump to circulate the fluid, and a manifold system to controlrecirculation and delivery of the fluid to the hydraulic pump (44).

Suitable hydraulic power fluid includes, for example, water, producedwater, water-based fluids, water-oil emulsions, inorganic saltsolutions, biodegradable plant-based hydraulic fluids, synthetic andnaturally occurring organic materials to create a hydraulic oil or fluidof similar properties. Base stock may be any of, for example, castoroil, glycol, esters, mineral oil, organophosphate ester,polyalphaolefin, propylene glycol or silicone. Commercially availablehydraulic fluids include, for example, Durad®, Fyrquel®, Houghton-Safe®,Hydraunycoil®, Lubritherm® Enviro-Safe, Pydraul®, Quintolubric®,Reofos®, Reolube®, and Skydrol®. The hydraulic fluid for the pump systemis selected based upon various properties including, for example, stableviscosity, chemical and physical stability, system compatibility, flashpoint, low volatility, low coefficient of expansion, minimal rustformation and fire resistance. In one embodiment, the hydraulic fluid iswater. In one embodiment, the hydraulic fluid is produced water which isre-circulated through the pump system (1).

Hydraulic fluid may be supplemented with one or more additives havingdesirable properties including, for example, the remediative capacity tocarry solids, reduce oil viscosity, create and extend worm-holes in thewellbore area, solvate dead heavy oil, and establish communication withadditional connate gas which assists fluid inflow. The additives mayinclude oils, butanol, esters, silicones, alkylated aromatichydrocarbons, polyalphaolefins, corrosion inhibitors, surfactants,dispersants, solvents, and other suitable chemical compounds. In oneembodiment, the additive is a brine-based, heavy oil solution whichcreates a light oil-in-water emulsion within the production fluid. Inone embodiment, the hydraulic fluid or supplemented hydraulic fluid maybe heated to a temperature ranging from about 30° to about 101° C.

The hydraulic fluid, which may be heated, is then drawn through ahydraulic pump (44) and injected into the lower flow tee (46) of thewellhead (48) and into the outer tubular string (22). Injection ofhydraulic fluid may be either batch or continuous injection. Thehydraulic fluid injection rate relates to the volume of fluid injectedin a well during hydraulic pumping. It will be understood by thoseskilled in the art that injection testing is initially conducted toestablish the rate and pressure at which fluid can be pumped into thetreatment target without damaging or fracturing the productionformation. In one embodiment, the hydraulic pump (44) injects at ratesranging from about 60 to 400 L/min. at an operating pressure rangingfrom about 8 to 24 MPa. The heated hydraulic fluid is injected into theannulus (22) until the inner tubular members (12) and the formation havebeen fully saturated, thereby “priming” the pump system. Continuedpumping lifts the mixture of hydraulic fluid and production fluidsthrough the inner tubular member (12) via the venturi effect describedabove. The venturi effect increases the kinetic energy of the fluid,providing sufficient lift to reach the surface (as indicated by thearrow “b”).

At the surface, a separator (50) separates the production fluids fromthe hydraulic fluid, directing the production fluid into one or moreoutflow lines (52) for further processing, and the hydraulic fluidthrough a filter (54) to the recirculation tank (42) for re-heating andre-entry into the pump system (1). The operation of a separator (50) iscommonly known to those skilled in the art. Briefly, a separator (50)comprises a cylindrical or spherical vessel used to separate oil, gasand water from the total fluid stream produced by the well. Separatorscan be either horizontal or vertical. Separators can be classified intotwo-phase and three-phase separators, with the two-phase type dealingwith oil and gas, and the three-phase type handling oil, water and gas.Gravity segregation is the main force that accomplishes the separationbased on fluid density. Additionally, inside the vessel, the degree ofseparation between gas and liquid will depend on the separator operatingpressure, the residence time of the fluid mixture and the type of flowof the fluid. Production separation begins with the well flowstreamsentering the vessel horizontally and hitting a series of perpendicularplates. This causes liquids to drop to the bottom of the vessel whilegas rises to the top. Gravity separates the liquids into oil and water.The gas, oil and water phases are metered individually as they exit theunit through separate outflow lines.

In one embodiment, the pump system (1) is installed within the well as apermanent production system. In one embodiment, the pump system (1) isportable, serving as a temporary work over, treating and clean outsystem, with outer and inner coils (not shown) substituting as the outerand inner tubular members (10, 12) respectively. In one embodiment, theouter coil has a diameter of 2 inches, while the inner coil has adiameter of 1.75 inches. The crossover member (16 b) may be modified toreceive a portion of the hydraulic fluid which is injected to power thepump system (1) within the inner coil, and divert the hydraulic fluid torun a combination of service tools off the end of the outer coil. Theouter coil may be wound to a spool to be conveyed via a coiled tubingunit to a desired service interval. The coiled tubing unit has anintegrated hydraulic pump, coil injector, and a production tank tohandle the circulated solids and liquids, all preferably mounted on onevehicle. Tools which may be run off the end of the outer coil include,for example, a bit for scraping the casing of the wellbore byreciprocating the coil; a sonic stimulator; a drill motor with a drillbit; or other suitable tools known to those skilled in the art.

In one embodiment, the pump system (1) includes a sonic stimulator whichemits acoustic waves to vibrate liquids and solids within the productionformation. As used herein and in the claims, the term “acoustic waves”means pressure waves propagating through the production formation. Inone embodiment, and without restriction to a theory, we believe theacoustic waves cause vibration at the molecular level of liquids andsolids in the producing zone, which assists in the mobilization andproduction of fluids. Molecular vibration may result in one or more ofthe following beneficial effects: repairs and removes naturallyoccurring or man-made formation damage; suspends wellbore damage insuspension fluid; removes scale, filter cake, wax, asphaltenes, bitumenor other materials; increases reservoir connectivity, injectivity andproduction; enhances stimulation fluid; stimulates selectively; anddecreases the viscosity of heavy oil to facilitate its mobilization.

The sonic stimulator can be incorporated with, for example, vertical,horizontal, liner, gas, oil, injection, and production wells. The sonicstimulator may be installed following completion of the well, andpreferably after injection of the heated power liquid into the annulus(36). In one embodiment, the sonic stimulator is placed in thehorizontal section of a well.

Once the pump system (1) has begun to lift the mixture of hydraulicfluid and production fluids to the surface, the sonic stimulator isinjected using coiled tubing to the desired depth in the well'shorizontal section. Use of a smaller diameter coiled tubing results inhigher pressure, while a larger diameter coiled tubing results in lowerpressure. Of course, pressure within the coiled tubing is dependent alsoon flowrate. The sonic stimulator may be injected into the wellhead (48)at the surface by a suitable crossover member or wellhead device (notshown). The coiled tubing is diverted to the discharge side of thehydraulic pump (44) which is adjusted to ensure that the injection ratesare suitable for both the pump system (1) and the sonic stimulator.

The hydraulic fluid injected into the coiled tubing actuates the sonicstimulator's internal hydraulic drive, which creates acoustic waves. Thehydraulic fluid exiting tubular jet members of the sonic stimulatorpermeates the formation, thereby creating a fluid environment whichenables acoustic waves to propagate through the formation productionzone. The penetration of the acoustic waves depends on numerous factors,including the amplitude and frequency of the waves, and the formationcharacteristics. In one embodiment, the acoustic waves may propagate upto about 12 feet outward within the formation. The acoustic wavesmobilize fluids towards the horizontal section of the wellbore. Eitheror both the acoustic waves and the jet members of the sonic stimulatorgenerate a negative pressure face at the perforations (38) of thehorizontal section or the well to further mobilize the production fluidsinto the wellbore. The jet members then push the production fluidstowards the vertical section of the well. The heated hydraulic fluidensures that the production fluids, particularly the heavy oil, remainmobilized and less viscous as they are lifted to the surface by the pumpsystem (1). At the surface, the separator (50) separates the productionfluids from the hydraulic fluid, directing the production fluid into oneor more outflow lines (52) for further processing, and the hydraulicfluid through a filter (54) to the recirculation tank (42) forre-heating and re-entry into the pump system (1).

An appropriate sonic stimulator for inclusion with the pump system (1)is selected based upon the quality and volume of hydraulic fluidrequired for the well. In one embodiment, the sonic stimulator (56) isincluded in the pump system (1) in which the quality of the hydraulicfluid is exceptional and the hydraulic fluid injection rate exceedsabout 60 L/min. In one embodiment, the sonic stimulator (82) is includedin the pump system (1) in which the quality of the hydraulic fluid ispoor and the hydraulic fluid injection rate is less than about 60 L/min.The flow rate required to create lift in the inner bore is typicallybetween about 30-300 L/min, at a pressure of about 7-14 MPa.

In general terms, the sonic stimulator (56) may be any device whichproduces acoustic waves from a stream of pressurized hydraulic fluid.Acoustic waves are pressure waves which propagate through the hydraulicfluid, and through the formation.

In one embodiment shown in FIGS. 4 to 7, the sonic stimulator (56)comprises an elongate body (58) defining a bore (60) extendingtherethrough, a plurality of tubular jet members (62), and a hydrauliccoupling (64). A crossover (66) connects the jet members (62) within theelongate body (58). In one embodiment, additional jet members (68) areincluded to provide extra lift for heavy solid production. In oneembodiment, jet members (62) are positioned at the end and the middlesections of the body (58).

As indicated in FIG. 7, the hydraulic fluid enters the sonic stimulator(56) via the coiled tubing (70) attached to the hydraulic pump (44) atthe surface. The hydraulic fluid passes through the bore (60) of thesonic stimulator (56) and into the hydraulic coupling (64). The jetmembers (62) expel the hydraulic fluid from both ends of the sonicstimulator (56). In one embodiment, at least one of the jet members (62)includes a nozzle (72) which produces a high velocity stream of fluid.This fluid stream may act as a cleaner during installation of the sonicstimulator (56), and contributes to the negative pressure face at theperforations (38). In one embodiment, at least one jet member (62) ismachined to project at an angle as shown in FIG. 6, such that theexpelled hydraulic fluid creates a vortex which provides lift toproduced solids. The hydraulic fluid exits the jet members (62) from themiddle of the sonic stimulator (56) by operation of the hydrauliccoupling (64).

Hydraulic couplings for high pressure hydraulic circuits are well knownin the art. In one embodiment shown in FIG. 8, the hydraulic coupling(64) is formed of two connectable cylindrical halves, with one halfcomprising elements (72, 74) and the other half comprising elements (76,78, 80). Elements (72, 74) are generally cylindrical and have opposedside apertures (72 a, 74 a). In one embodiment, apertures (74 a) have alarger diameter than apertures (72 a). During manufacture, element (72)is heat-shrunk over element (74) with apertures (72 a, 74 a) in axialalignment.

Element (76) is generally cylindrical defining a bore extendingtherethrough to allow insertion of element (78). Element (76) include aplurality of apertures (76 a, 76 b) in a face plate. In one embodiment,a plurality of smaller diameter apertures (76 a) are arranged on thecircumference of the face plate of element (76) to encircle a largerdiameter, central aperture (76 b). Element (78) is generally cylindricaldefining a bore extending therethrough and having two opposed end faces(78 a, the other shown in phantom in FIG. 8). Each face (78 a) has aplurality of apertures (78 b, 78 c). In one embodiment, a plurality ofsmaller diameter apertures (78 b) are arranged on the circumference ofthe face (78 a) to encircle a larger diameter, central aperture (78 c).Opposed side apertures (78 d) (shown in phantom in FIG. 8) are presentin the mid-section of element (78). In one embodiment, element (78) isnotched at its ends to load into elements (76, 80). Element (80) isgenerally cylindrical defining a bore extending therethrough to an endface (80 a). The end face (80 a) has a plurality of apertures (80 b, 80c). In one embodiment, a plurality of smaller diameter apertures (80 b)are arranged on the circumference of the end face (80 a) to encircle alarger diameter, central aperture (80 c).

In one embodiment, when elements (76, 78, 80) are engaged, the faceplate apertures of elements (76) and (78) are offset to avoid alignment.Further, the number of apertures of elements (76, 78) differs. In oneembodiment, seven apertures (76 a) in element (76) feed six apertures(78 b) in element (78). Elements (76, 78, 80) insert into elements (72,74) of which threads (72 b, 74 b) couple together the two halves to formthe hydraulic coupling (64).

During operation, the hydraulic fluid enters the hydraulic coupling (64)through apertures (76 a, 76 b). Since apertures of element (78) areoffset to apertures of element (76), element (78) rotates as thehydraulic fluid passes through element (78) into element (80). Hydraulicfluid which enters the central aperture (76 b) passes into the centralaperture (78 c) of rotating element (78). Hydraulic fluid exits fromapertures (78 d) and from element (80) to feed the jet member (60). Inone embodiment, the jet member (60) includes a nozzle (72).

Elements (72, 74) serve as a resonance chamber which forms pressurepulses as the hydraulic fluid passes through the coupling. The frequencyof the pulses depends upon the number of apertures which transfer thehydraulic fluid from apertures (78 b) to apertures (78 d). During eachrotation of element (78), a pulse emits as streaming hydraulic fluidhits (i.e., pulses) the resonance chamber formed by elements (72, 74).The wave frequency is determined by the number of pulses per secondwhich can be used to calculate the wavelength being exerted on theproduction formation. The pressure at which the hydraulic fluid isinjected by the hydraulic pump (44) determines the amplitude of thewaves and the magnitude of the wave action upon the productionformation. The pressure pulses emitted by the hydraulic coupling (64) ofthe sonic stimulator (56) propagate along the body (58) to create asimilar effect (i.e., pulsation) at the jet members (62) at the ends ofthe sonic stimulator (56). The result is a high cleaning efficiencyacross greater areas of the wellbore. In one embodiment, the sonicstimulator (56) can stimulate or clean in the range of about 18 to 48inches in radius, or up to about 8 feet in diameter.

In one embodiment, the sonic stimulator (56) creates pulses with afrequency of about 80 to 250 Hz, with about 30 hp of pulse pressure atthe sonic stimulator (56). In one embodiment, the hydraulic coupling(64) requires a pressure range of approximately 5 to 7 MPa back pressurein the sonic stimulator (56) to operate at this rate. In one embodiment,fluid rates range from about 30 to 350 L/min at about 7 to 24 MPa,Preferably, the flow rate is about 100-200 L/min at about 7-14 MPa. Itis understood by those skilled in the art that the higher the fluidrate, the higher the pressure, and thus, the greater the pulse pressure(measured in hp) generated at the sonic stimulator (56). Low frequency,high amplitude applications may be designed, which may be achieved withfluid rates less than about 30 L/min, and as low as about 10 L/Min.

In one embodiment shown in FIGS. 9 to 10, the sonic stimulator (82)comprises an elongate housing (84) defining a bore (86) extendingtherethrough to house a valve assembly comprising a valve retainer (88)and a valve (90), a plurality of jet members (92), a resonance section(94), a piston assembly (96, 98, 100) which is moveable between a firstposition and a second position, and biasing means for biasing the piston(100) towards the first position. The piston (100) fits withinreasonably close tolerance to the inside diameter of the housing (84)and divides the sonic stimulator (82) into a proximal section and adistal section. The piston need not fit fluid-tight within the bore,therefore piston rings or seals are not necessary. When fluid is pumpedinto the proximal section, it passes through the valve assembly, throughthe resonance assembly and against the piston (100). In one embodiment,the jet members (92) are rotatable on the resonance section (94). In oneembodiment, one jet member is an end jet member (93) disposed at thedistal end of the sonic stimulator. In one embodiment, the biasing means(102) is a coil spring.

The hydraulic fluid enters the sonic stimulator (82) via the coiledtubing (70) attached to the hydraulic pump (44) at the surface. Thefluid passes into the bore (86) of the sonic stimulator (82) through theapertures (88 a) of the valve retainer (88) to open the valve (90). Thevalve (90) allows the passage of the hydraulic fluid to the jet members(92). The jet members (92) are ring shaped and are rotatably mounted onthe resonance section (94). Resonance apertures (94 a) in the resonancesection (94) are each sized having a diameter larger than that ofapertures (92 b). The fluid passes through large-diameter apertures (94a) and exits small-diameter circumferential apertures (92 b) of the jetmembers (92), when the apertures are aligned. The circumferentialapertures (92 b) are machined at a tangential angle so that fluidexiting the jet members (92) causes them to rotate. When the apertures(92 b, 94 a) of the jet members (92) and resonance assembly (94) align,a resonance chamber forms and a pressure pulse is emitted. The number ofapertures of the jet members (92) and the speed at which the jet members(92) rotate determine the frequency of the pressure pulses. The flowrateat which the hydraulic fluid is injected determines the power.

In one embodiment, the hydraulic fluid passes through the apertures (96a) of the rod retainer (96) to act on the piston (100) against thebiasing means (102). The force of the piston (100) compresses thebiasing means (102 and expels fluid from the distal portion through theend jet member (93) and nozzles (104). Once the biasing means (102) ismaximally compressed, pressure builds up within the resonance chamber(94), causing closure of the valve (90). The hydraulic fluid continuesto exit the jet members (92) until the biasing means (102) overcomes thepressure exerted by the fluid, forcing the fluid backwards. The piston(100) increases the velocity of the hydraulic fluid, which creates afrequency variation by increasing the speed at which the jet members(92) rotate. As the biasing means (102) retracts, it pulls hydraulicfluid from outside the sonic stimulator through the end jet member (93)and nozzles (104). In one embodiment, the end jet member (93) comprisesthree nozzles (104). The hydraulic fluid is expelled on the next cycleof the piston (100), creating a pulse from the one or more nozzles(104). Pulsation at both ends of the sonic stimulator (82) increases theefficiency of the sonic stimulator (82) on the production formation.Once the biasing means (102) has fully retracted, the pressure offurther injected fluid into the sonic stimulator bore (86) opens thevalve (90) and the cycle repeats.

The valve (90) may comprise a one-way valve such as a ball valve, or acheck valve.

Aspects of the present invention may be combined with alternativeenhanced oil recovery techniques. For example, alkali-surfactant (AS)flooding is an established enhanced oil recovery technique used inconventional oil reservoirs. These chemicals carried in the injectionbrine lower the oil/water interfacial tension mobilizing the flow ofsome of the trapped oil.

Alkali-surfactant flooding with polymers has been more recently employedto improve EOR flooding of moderately heavy oil. Without polymerflooding or SAGD efforts only 20% or less of the OIP (Oil in Place) maybe recovered by primary production techniques due to solution gas drive.With pressure draw down and loss of the gas drive the reservoir energybecomes too depleted for further cold pumping to be economically viable.

It is known that certain types of AS injection, without the addition ofpolymers, can be used for enhanced non-thermal heavy oil recovery. ASinjection, under shear conditions, can reduce the interfacial tensionbetween oil and water to values that allow for oil-in-water orwater-in-oil emulsions to form providing enough viscosity and selfdiversion to sweep additional HOIP (Heavy Oil in Place).

The combination of a sonic stimulator tool (56 or 82) of the presentinvention and AS flooding may provide efficient recovery of HOIP. Thehydraulic power fluid may include additives to perform AS flooding. Thesonic stimulator passes the fluid into the formation under shearconditions with uniform propagation, which may stabilize in situemulsions. Thus, the mobility ratio between water and heavy oil may bereduced and ultimately improve heavy oil sweep efficiencies. These sonictools can be placed and landed on coiled tubing either in the horizontalsection of heavy oil wells or in an injection well strategically placedin a water flood pattern. In a horizontal well installation the taperedinjection of AS brine under sonic conditions may generate an energizedchemical plume which will sweep ‘toe to heel’ heavy oil. A taperedinjection of AS brine is one where the concentration of additives isvaried according to the position of the sonic tool in the wellbore. Oneskilled in the art will understand the the “toe” of a horizontal portionof a well comprises the distal end of the well, away from the verticalsection. In an injection well, the same energized chemical plume willsweep emulsified heavy oil outwards to a set of surrounding productionwells.

The acoustic waves, which applied at a suitable frequency and amplitude,generated by the sonic stimulators may provide deep uniform penetrationof the power fluid, which may have a designed chemistry, and may enhanceor generate heavy oil water emulsions for flooding purposes.

The present invention is advantageous over designs of the prior art. Thehydraulic actuated pump system (1) lifts production fluids, solids(i.e., sand, shale, clay) and re-circulating hydraulic fluid from thevertical section of a wellbore. The hydraulic fluid and productionfluids conveniently drive the system. The hydraulic fluid may comprisewater or re-circulated, produced water, thus minimizing cleaning andexpense. Further, the hydraulic fluid may be supplemented with additivesto apply direct chemical treatment of the production formation,replacing the commonly used drip systems which lack control overchemical placement. Low bottom hole pressure wells may be worked overwithout requiring nitrogen. Further, the pump system eliminates therequirement for complex, downhole moving parts, and avoids heat issueswith thermal floods.

Systems which include moving parts downhole in thermal floods damagequickly and wear out due to high operating temperatures. In the presentinvention, this is less likely to occur as there are fewer downholemoving parts, temperature does not affect the pump parts, temperaturewill affect the fluid if it reaches boiling under pressure, but if thisoccurs it will have even greater velocity to carry fluid from theannulus.

The pump system including a sonic stimulator thus permits injection,cleaning, stimulation and production without requiring well shut downfor any of these activities. The pump system may be installedpermanently within the well, or modified to be portable, serving as atemporary work over, treating and clean out system.

Where power requirements for the pump system (1) or any componentthereof is described, one skilled in the art will realize that anysuitable power source may be used, including, without limitation,electrical systems, rechargeable and non-rechargeable batteries,self-contained power units, or other appropriate sources.

In one embodiment, the production of fluids may be enhanced by the useof chemical additives in the power fluid for the jet pump system, or thepower fluid to drive the sonic stimulator, or both.

As will be apparent to those skilled in the art, various modifications,adaptations and variations of the foregoing specific disclosure can bemade without departing from the scope of the invention claimed herein.

What is claimed is:
 1. A method of enhanced oil recovery from a formation, comprising the steps of: (a) installing a sonic stimulator into an injection wellbore, or a horizontal section of a wellbore, on the end of coiled tubing; (b) activating the sonic stimulator with a liquid hydraulic power fluid to produce acoustic waves having a frequency of about 80 Hz to about 250 Hz, and inject hydraulic power fluid into the formation; (c) using the liquid hydraulic power fluid to sweep oil towards one or more proximate production wells, or from the horizontal section of a wellbore towards a vertical section of the wellbore.
 2. The method of claim 1, wherein the liquid hydraulic power fluid comprises water, produced water, water-based fluids, water-oil emulsions, inorganic salt solutions, biodegradable plant-based hydraulic fluids, or synthetic and naturally occurring organic materials.
 3. The method of claim 2, wherein the liquid hydraulic power fluid is supplemented with one or more additives comprising oils, butanol, esters, silicones, alkylated aromatic hydrocarbons, polyalphaolefins, or corrosion inhibitors.
 4. The method of claim 3, wherein the one or more additives comprises a brine-based, heavy oil solution for creating a light oil-in-water emulsion within the production fluids.
 5. The method of claim 2 wherein the liquid hydraulic fluid or the supplemented hydraulic fluid is heated to a temperature ranging from about 30° to 101° C. 